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PXI 4472 Phase Characterization

We need to characterize the phase change (10 to 20KHz) that the 4472 introduces. What technique would I use to do this? Is there a method to loopback the input signal so that we can look at both the input/output on a scope?



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Also we are using the 4472 AC coupling so that is introducing phase error. We are using Labview to do the FFT to get the phase info - also was curious if that adds any phase error. 

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Hello davidhi,


Can you elaborate a bit more in what is that you are trying to measure and why?


Diego H

National Instruments

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We are measuring a MEMS microphone. In the test system the output of the mic goes through a filter/gain module and then is routed to the 4472. We need to know the phase at the microphone output. In order to do this we need to characterize the test system. One phase error concern is the 4472. AC coupling is being used so that will affect the phase. All phase errors need to be characterized. This measurement is a customer test requirement. Up until this point we had been just using the relative phase; the system was only calibrated for magnitude. 

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In order to characterize the device you first need a controlled known signal, you can trust. Then, you can make the measurements needed and correlate the data to the actual expected values. 

A customer has an explanation in how they accomplish it in this forum https://forums.ni.com/t5/Multifunction-DAQ/Where-can-I-find-the-amplitude-and-phase-frequency-respon...


Diego H

National Instruments

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